Extensible framework for capturing feature information in a neutral format

ABSTRACT

Flexible framework within a CAD application program is described that serves as a neutral format for feature information relating to modeling data for a solid body. The framework is hierarchical in nature to allow for ease of use and universal access to the design data. The hierarchical framework is independent of the underlying feature information as well as independent of the underlying CAD program.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to handling feature informationin a parametric feature-based solid modeler, and in particular, to amethod, apparatus, and article of manufacture for providing anextensible framework for capturing feature information in a neutralformat for computer programs that build three d models based on formfeatures.

2. Description of the Related Art

The use of Computer Aided Design (CAD) application programs is wellknown in the art. Some CAD programs provide standard objects that helpusers create documents, graphical presentations, etc. However, thesestandard objects provide only limited assistance and do little to helpthe user connect standard CAD components, define new components, ordefine methods of manipulating the components within the CAD program.

Further, most CAD programs have representations of objects that areunique to that CAD program. Each CAD designed part has features that areaccessed by various people throughout the design and manufacturingprocess. However, designers, manufacturers, and users typically usedifferent software programs with different formats to analyze and accessthe CAD data, creating confusion as well as incomplete data retrievalfor all parties concerned.

Consequently, there is a need in the art for improved techniques toaccess CAD designed part data. Further, there is a need in the art forimproved techniques for formatting the data such that the variousparties that desire access to the CAD part data can obtain theinformation desired.

SUMMARY OF THE INVENTION

To address the requirements described above, the present inventiondiscloses a method, apparatus, and article of manufacture for executingan extensible schema or framework for representing feature data in acomputer, wherein the flexible framework provides data in a neutralformat. The flexible framework serves as a database for users ofmultiple disciplines and multiple end products to access and use the CADdata.

All of the design intent represented in the feature model is accessibleby the flexible framework in order to provide more capabilities to eachuser.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers representcorresponding parts throughout:

FIG. 1 is an exemplary hardware environment used to implement thepreferred embodiment of the invention;

FIG. 2 illustrates relating to the hierarchical and modeling frameworksof the present invention; and

FIG. 3 is a flowchart that illustrates the general logic of performingthe steps of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, reference is made to the accompanyingdrawings which form a part hereof, and which is shown, by way ofillustration, several embodiments of the present invention. It isunderstood that other embodiments may be utilized and structural changesmay be made without departing from the scope of the present invention.

Overview

The present invention is a Computer Aided Design (CAD) program thatincludes an Application Programming Interface (API) that allows forfeatures in a parametric solid modeling system to be represented in aneutral, extensible format. The representation is independent of theparticular underlying feature implementation. Enhancements to theunderlying feature representations can be accomplished without impactingthe user of the framework, thus supporting the development of systemswhich can evolve without compromising the binary compatibility ofinteracting applications.

The framework of the present invention allows information to beretrieved at different levels for optimal performance. It can be usedfor purposes of creating, querying, or editing features and can be seenas a representation-neutral language for the manipulation of features inparametric feature based solid modeling systems. The framework isparticularly suitable for use in an API as it insulates the client ofthe API from internal details of the modeling system. It is applicableto any CAD program that supports built-in features in the context of aparametric feature based solid modeler. It defines a hierarchy ofobjects, and methods on these objects, which together contain all theinformation used in the creation and regeneration of any feature in thesystem. The information represented includes the type of feature,hierarchical characterization of the feature, the parameters driving howthe feature is located and terminated on the part.

The basic classes used in the framework fall under the groupings offeature descriptors and feature informers. For each type of feature alldefining parameters are properly represented. Feature informers arefurther subdivided into feature locators, feature terminators, andfeature combiners. The following diagram illustrates how differentclasses in the framework are related. The framework can be easilyextended to accommodate new types of features, different ways oflocating features, etc.

The framework of the present invention allows for seamless transitionsbetween developers of CAD drawings and other programs or users that needto access the parts that the CAD drawings represent. Each person thatmust access the drawing can access the information he or she wantsbecause the framework allows for multiple levels of access.

Hardware Environment

FIG. 1 is an exemplary hardware environment used to implement thepreferred embodiment of the invention. The present invention istypically implemented using a personal computer 100, which generallyincludes, inter alia, a processor 102, random access memory (RAM) 104,data storage devices 106 (e.g., hard, floppy, and/or CD-ROM disk drives,etc.), data communications devices 108 (e.g., modems, networkinterfaces, etc.), monitor 110 (e.g., CRT, LCD display, etc.), mousepointing device 112 and keyboard 114. It is envisioned that attached tothe personal computer 100 may be other devices such as read only memory(ROM), a video card, bus interface, printers, etc. Those skilled in theart will recognize that any combination of the above components, or anynumber of different components, peripherals, and other devices, may beused with the computer 100.

The personal computer 100 usually operates under the control of anoperating system 116. One or more computer programs 118 that operateunder the control of the operating system 116 are typically accessed viaan Application Programming Interface (API) 120. Typically with thepresent invention, computer program 118 is a CAD program, but anyprogram can implement the present invention. API 120 allows otherprograms and users to access computer program 118. Application 1 122uses API 120 to interface and use computer program 118. Application 1122 is representative of one or more applications or other interfacesthat use API 120 to access computer program 118.

The API 120 provides a uniform referencing mechanism for allapplications of the computer program 118. The API 120 allows applicationdevelopers to refer to objects within the computer program 118 in auniform manner without requiring the application to account for specificdetails of which application created the object referred to. Forexample, designer interface 126 can create an object to be used withcomputer program 118 through the API 120 that application 1 122 hasaccess to and can use without conversion of the details of therepresentation of the object or details of the creation of the objectbeing attached to the object created.

Within the computer program 118, a modeling framework 202 is used torepresent the solid body that is being modeled. Within the API 120, thepresent invention adds a hierarchical framework 200 that converts ormaps the modeling framework 202 to a framework that is easily accessedby application 1 122.

Generally, the computer program 118, API 120, application 1 122,hierarchical framework 200, and modeling framework 202 compriseinstructions and/or data that are embodied in or retrievable from acomputer-readable device, medium, or carrier, e.g., the data storagedevice 106, a remote device coupled to the computer 100 via the datacommunications device 108, etc. Moreover, these instructions and/ordata, when read, executed, and/or interpreted by the computer 100 causethe computer 100 to perform the steps necessary to implement and/or usethe present invention.

Thus, the present invention may be implemented as a method, apparatus,or article of manufacture using standard programming and/or engineeringtechniques to produce software, firmware, hardware, or any combinationthereof. The term “article of manufacture” (or alternatively, “computerprogram product”) as used herein is intended to encompass a computerprogram accessible from any computer-readable device, carrier, or media.Of course, those skilled in the art will recognize many modificationsmay be made to this configuration without departing from the scope ofthe present invention.

Those skilled in the art will recognize that any combination of theabove components, or any number of different components, includingcomputer programs, peripherals, and other devices, may be used toimplement the present invention, so long as similar functions areperformed thereby.

Modeling the Object

FIG. 2 shows details relating to the hierarchical and modelingframeworks of the present invention. As application 1 122 creates a CADdrawing, computer program 118 is used as a modeling tool toparametrically model a solid body. Within the computer program 118, amodeling framework 202 is used to represent the solid body. Typically,the modeling framework 202 is object oriented, and contains object 204.Modeling framework 202 may contain more objects 204; one object 204 isshown for ease of presentation.

Located within each object 204 is a feature 206. A feature 206 may be aform feature, such as a hole, extrusion or fillet, or a work or datumfeature, such as work axis or work plane. Further, object 204 cancontain many features 206, and one feature 206 is illustrated for easeof presentation.

The hierarchical framework 200 of the present invention uses theinformation relating to the feature 206 of the modeling framework 202and organizes it in a different manner. The hierarchical frameworkgenerates a neutral representation of the feature 206 and stores theneutral representation in defined classes to allow for ease of access tothe information for purposes of query, creation, or editing.

As modeling of a solid body takes place, lines, geometric shapes,fillets, through and blind holes, and other qualities and features ofthe solid body are created that will be used for analysis and productionlater in the design process. As these features 206 are stored in anobject-oriented sense in the modeling framework 202, the hierarchicalframework 200 of the present invention provides the design data toapplication 1 122 through API 120 in a different format. The feature 206is unchanged, but is now more readily accessible to application 1 122 ondemand.

Hierarchical Framework

The hierarchical framework 200 of the present invention allows differentapplications to access CAD drawing information at different levels in aformat that is not biased towards any of the potential applications,i.e., a “neutral” format. Each level of the hierarchical framework 200is derived from the information stored in the level above itself.

As shown in FIG. 2, once application 1 122 is utilizing the computerprogram 118 to model the solid body, the framework 200 of the features206 of the solid body is further broken down into descriptors 208 andinformers 210. Descriptors 208 provide information on the data definingthe shape of the feature 206, independent of the feature 206 location ortermination. A specific descriptor 212, such as a hole descriptor or afillet descriptor, is derived from a descriptor 208, and usuallycontains specific feature elements 214, such as the diameter of acircle, the length of a line, the angle that a line takes with respectto the horizontal or vertical axes, etc.

For example, a corner on an object is rarely exactly sharp; there isusually some rounding of the corner. There will be in the framework aspecific feature element 214 that allows the application 1 122 toretrieve or specify values for the fillet radius. This specific featureelement 214 (the radius) is accessed through a specific descriptor 212,in this case, a fillet descriptor. The descriptor 208 does not have aconcrete instance within the hierarchical framework 200; instead, it isan abstract class that allows for uniform access to all specificdescriptors 212. The hierarchical framework 200 can be extended intodeeper levels if desired.

The informer 210 class allows the application 1 122 to specifyinformation about the feature 206 that relate the feature 206 toexternal parameters. Locator 216, which is derived from informer 210,allows the application 1 122 to determine where the feature 206 will beplaced on the drawing. Specific locator 218, such as a concentriclocator or a co-linear locator, is derived from a locator 216, andusually contains locator elements 220, such as angles and distances.

For example, a hole can be placed on a modeled body concentrically witha cylindrical surface. Thus, the hierarchical framework 200 provides aspecific locator 218, namely a concentric locator that corresponds tothis type of hole location procedure. Using this specific locator 218,the user can query or set the hole position through the locator element220, which represents a reference to the cylindrical surface inpositioning the hole. The locator element 220 is accessed through thespecific locator 218.

The locator 216 does not have a concrete instance within thehierarchical framework 200; instead, it is an abstract class that allowsfor uniform access to all specific locators 218. The hierarchicalframework 200 can be extended into deeper levels if desired.

Specific locator 218 can also specify a relative location which allowsthe application 1 122 to determine where the feature 206 will be placedrelative to another feature, whether tangent to, concentric with,aligned with, angled with respect to, or any other location informationthat draws on items external to the feature 206 itself.

Terminator 222 allows an application 1 122 to determine the terminationcharacteristics of a feature 206. Terminator 222 allows for blind,through, planar, and from/to terminations, as well as other terminationsof feature 206.

For example, a hole in a modeled body can have a certain depth, which isreferred to as a blind hole. Thus, the hierarchical framework 200provides a specific terminator 224 called a blind terminator. There willbe in the hierarchical framework 200 a specific terminator element 226which corresponds to the depth of the blind hole that allows application1 122 to retrieve or specify values for the blind hole depth. Thisspecific terminator element 226 (the depth) is accessed through aspecific terminator 224, in this case, a blind terminator. Theterminator 222 does not have a concrete instance within the hierarchicalframework 200; instead, it is an abstract class that allows for uniformaccess to all specific terminators 224. The hierarchical framework 200can be extended into deeper levels if desired.

Combiner 228 allows the application 1 122 to combine feature 206 withother features 206, whether joining, intersecting, cutting, basal, orother combinations.

The framework 200 can be easily extended to accommodate new types offeatures, different ways of locating features, etc. Further, additionalclasses, specific instances of classes, and features of the specificinstances of each class are available for descriptor 208, informer 210,and any additional extended class that the framework is designed for.

As applications traverse the framework 200, applications can access theinformation stored in each class (descriptor 208 and informer 210) aswell as each subclass (specific descriptor 212, feature descriptorelements 214, locator 216, specific locator 218, locator element 220,terminator 222, specific terminator 24, terminator element 226, andcombiner 228) differently so each application can obtain the informationthey need to complete their task. Different levels of access can begiven to allow some applications to only access class information, whereother applications can be given full access to access any informationwithin the framework 200. Further, some applications can be givenread-only access to allow for limited entry access into the framework200.

Flowchart

FIG. 3 is a flowchart that illustrates the general logic of performingthe steps of the present invention.

Block 300 represents performing the step of creating a hierarchicalframework, the hierarchical framework distinct from the modelingframework.

Block 302 represents performing the step of creating at least one classwithin the hierarchical framework.

Block 304 represents performing the step of generating a neutralrepresentation of the feature of the parametrically modeled solid body.

Block 306 represents performing the step of storing the neutralrepresentation as an entry in the hierarchical framework.

Conclusion

This concludes the description of the preferred embodiment of theinvention. The following describes some alternative embodiments foraccomplishing the present invention.

For example, any type of computer, such as a mainframe, minicomputer,workstation or personal computer, could be used with the presentinvention. In addition, any software program, application or operatingsystem having a user interface could benefit from the present invention.

The above teaching also supports additional functions that may also beimplemented using the hierarchical framework of the present invention.In addition, the hierarchical framework can be integrated closely witheach application program by any number of different methods.

In summary, the present invention discloses a method, apparatus, andarticle of manufacture for executing an extensible schema or frameworkfor representing feature data in a computer, wherein the flexibleframework provides data in a neutral format. The flexible frameworkserves as a database for users of multiple disciplines and multiple endproducts to access and use the CAD data. All of the properties of themodeled solid body are accessible by the flexible framework in order toprovide more capabilities to each user.

The foregoing description of the preferred embodiment of the inventionhas been presented for the purposes of illustration and description. Itis not intended to be exhaustive or to limit the invention to theprecise form disclosed. Many modifications and variations are possiblein light of the above teaching. It is intended that the scope of theinvention be limited not by this detailed description, but rather by theclaims appended hereto.

What is claimed is:
 1. A computerized method of representing a feature of a parametric solid model comprising: obtaining information relating to a feature of a parametric modeled solid body; storing the information in object instances represented in a hierarchical framework wherein the hierarchical framework comprises: (a) an abstract descriptor class for a feature, wherein an instance of an implemented descriptor classes provides geometric information of a feature; and (b) an informer class for a feature, wherein the informer class provides information about the feature that relates the feature to external parameters, wherein the informer class is selected from a group comprising: (i) an abstract feature locator class that provides location information regarding where to place a feature on a drawing; (ii) an abstract feature terminator class that provides termination characteristics of a feature; and (iii) an abstract feature combiner class that provides how to combine a feature with a second feature of the parametrically modeled solid body.
 2. The method of claim 1 wherein the location information comprises information that locates a feature with respect to another feature of the parametrically modeled solid body.
 3. The method of claim 1 wherein the abstract descriptor class and informer class provide methods for accessing information contained in instances of the classes.
 4. A system for representing a feature of a parametric solid model comprising: (a) a parametric modeled solid body having one or more features comprised of feature information; (b) a hierarchical framework utilized to represent the parametric modeled solid body, the hierarchical framework comprising: (i) an abstract descriptor class for a feature, wherein an instance of an implemented descriptor class provides geometric information of a feature; and (ii) an informer class for a feature, wherein the informer class provides information about the feature that relates the feature to external parameters, wherein the informer class is selected from a group comprising: (1) an abstract feature locator class that provides location information regarding where to place a feature on a drawing; (2) an abstract feature terminator class that provides termination characteristics of a feature; and (3) an abstract feature combiner class that provides how to combine a feature with a second feature of the parametrically modeled solid body.
 5. The system of claim 4 wherein the location information comprises information that locates a feature with respect to another feature of the parametrically modeled solid body.
 6. The system of claim 4 wherein the abstract descriptor class and informer class provide methods for accessing information contained in instances of the classes.
 7. An article of manufacture comprising a program storage medium readable by a computer hardware device and embodying one or more instructions executable by the computer hardware device to perform a method for representing a feature of a parametric solid model, the method comprising: (a) obtaining information relating to a feature of a parametric modeled solid body; (b) storing the information in object instances represented in a hierarchical framework wherein the hierarchical framework comprises: (i) an abstract descriptor class for a feature, wherein an instance of an implemented descriptor classes provides geometric information of a feature; and (ii) an informer class for a feature, wherein the informer class provides information about the feature that relates the feature to external parameters, wherein the informer class is selected from a group comprising: (1) an abstract feature locator class that provides location information regarding where to place a feature on a drawing; (2) an abstract feature terminator class that provides termination characteristics of a feature; and (3) an abstract feature combiner class that provides how to combine a feature with a second feature of the parametrically modeled solid body.
 8. The article of manufacture of claim 7 wherein the location information comprises information that locates a feature with respect to another feature of the parametrically modeled solid body.
 9. The article of manufacture of claim 7 wherein the abstract descriptor class and informer class provide methods for accessing information contained in instances of the classes. 